improve setup_unique_search
Coccinelle has a feature where if a header file occurs only once in the code base, it can be used, even if there is no -I option that leads to it. This is implemented by parsing_c/includes.ml in the function setup_unique_search. If Coccinelle is used with the following options (for any Linux kernel):
--relax-include-path -I /home/julia/linux -I /home/julia/linux/include
this function is quite slow, particularly the function loop with parameters good and bad, which can end up being called with lists of length over 50 000. There should be some way to make this more efficient.
The semantic patch and the C code are irrelevant. In particular, it is not necessary for the C code to contain any includes. This is something that is triggered by the use of the --relax-include-path option.